Some of the prior art spray devices will now be described in conjunction with the accompanying drawings, namely, FIGS. 7 to 10, giving a typical example of rotary atomizing spray device (see Patent Document 1 listed below). A rotary atomizer 101 is, as shown in FIG. 7, provided with a handle 110, an adjusting unit 112 above the handle 110, and a spray nozzle 114 at a distal end ahead of the adjusting unit 112.
The handle 110 includes a grip 120 at the bottom of which there are provided an air pipe connector 124 coupling the handle with a high-pressure air pipe 122 conducting to a compressor (not shown), and an air-adjustor thumb screw 126 adjusting pressure of pressurized air supplied to the rotary atomizer 101. As depicted in FIG. 10, the air-adjustor thumb screw 126 displaces a 1st-valve regulator 129 of a first valve 128 to regulate the opening/closing of the first valve 128 that is positioned in a pressurized air duct 127 in communication with the air pipe connector 124.
The adjusting unit 112 is provided, at its center, with a gun body 130, a trigger lever 134 of which rotary shaft links it to a cam lever 132, a hook 136, and a paint pipe connector 140 that is to couple a paint supply pipe 138 conducting to a paint tank (not shown). A spring member 133 urges the cam lever 132 to rotate in clockwise direction in FIG. 7.
The trigger lever 134 is, as can be seen in FIG. 10, pivotally connected to the gun body 130 by means of a trigger-lever rocking member 135. A second valve 137, which is located on the downstream side of the first valve 128 in the context of air flow through the pressurized air duct 127, has its coupling member 150 abutting against the trigger lever 134 at its middle segment. The second valve 137 has a compression spring 139 that urges the trigger lever 134 to pivot forward. A 2nd-valve regulator 151 of the second valve 137 is displaced by the coupling member 150 so as to regulate the opening/closing of the second valve 137.
With the trigger lever 134 being pulled to at the least half of its full back stroke as depicted in FIG. 7, the pressurized air is supplied to an air motor (not shown) to force a bell 206 to revolve. The trigger lever 134 is able to be locked in such a half a back stroke position or ½ back stroke position by engagement of a middle step 148 of a cam 132C in the cam lever 132 with a cam pin 149 that is fixed with the gun body 130.
With the trigger lever 134 being pulled to its full back stroke as depicted in FIG. 8, the pressurized air is further supplied to force the bell 206 revolve and to permit paint to be supplied and atomized, so that the atomized paint can be sprayed through the bell 206. The trigger lever 134 is also able to be locked in such a full back-stroke position by pulling the trigger lever 134 further proximally so as to overcome the repulsive force from the second valve coupling member 150 till the cam pin 149 is engaged with a front end 152 of the cam 132C. In this way, adjusting a position of the cam pin 149 between the middle step 148 and the front end 152 to fix the position in either of them permits the paint to be sprayed with a controlled rate as desired.
In order to release the trigger lever 134, namely, to return it to its home position to bring the spraying to rest, an operator may simply use his or her thumb and press a projection 160 of the trigger lever 134 kept in its ½ back-stroke position as in FIG. 7 so as to rotate the cam lever 132 in the clockwise direction. This allows the cam pin 149 to move from the middle step 162 to the a rear end 164 of the cam 132C, and the trigger lever 134 released from confinement by the cam lever 132 becomes free to retrace its way as shown in FIG. 9.
The adjusting unit 112 is provided, at its upper rear segment, with a sprayed-paint adjustor thumb screw 170 and a shaping-air adjustor thumb screw 172. As shown in FIG. 10, the sprayed-paint adjustor thumb screw 170 alters a relative position of a 3rd-valve regulator 178 of a third valve 176 to the trigger lever 134 where the third valve is located in a paint duct 174 conducting to the paint pipe connector 140. Thus, turning the sprayed-paint adjustor thumb screw 170 permits the paint to be supplied or sprayed with a controlled rate as desired while the trigger lever 134 is being pulled.
The shaping-air adjustor thumb screw 172 displaces a 4th-valve regulator 182 of a fourth valve 180 on the downstream side of the second valve 137 in the pressurized air duct 127, so as to regulate the opening/closing of the fourth valve 180.
The handle 110, generally consisting of the grip 120 and the gun body 130, is fabricated by means of the aluminum die casting, and alternatively, it may be made of die cast aluminum and rigid plastic (see Patent Documents 2 and 3 listed below). The gun body may be molded and/or machined of steels, steel alloys, and/or other substances of tough compositions (see Patent Document 4 listed below). Alternative embodiments have been disclosed like the gun body that is molded of composite resin, as a whole (see Patent Documents 5 and 6), or the one that is made of electrically insulating material suitable for a use of the rotary atomizing and electrostatic coating (see Patent Document 7).
A further alternative embodiment has been disclosed which has an aluminum die cast spray gun body coated with fluorocarbon resin (see Patent Document 8).
Patent Document 1:
    Japanese Patent Preliminary Publication of Unexamined Application No. 2004-321844Patent Document 2:    Japanese Patent Preliminary Publication of Unexamined Application No. H6-190310Patent Document 3:    Japanese Patent Preliminary Publication of Unexamined Application No. H7-275749Patent Document 4:    Japanese Patent Preliminary Publication of Unexamined Application No. H9-511687Patent Document 5:    Japanese Patent Preliminary Publication of Unexamined Application No. 2006-43593Patent Document 6:    Japanese Patent Preliminary Publication of Unexamined Application No. 2002-523214Patent Document 7:    Japanese Patent Preliminary Publication of Unexamined Application No. H7-70557Patent Document 8:    Japanese Patent Preliminary Publication of Unexamined Application No. H7-275747